1. Field of the Invention
The present invention relates to devices for converting the kinetic energy of fluid currents into other forms of energy and more particularly to devices for converting the kinetic energy of wind currents into electrical energy.
2. Description of the Related Art
Renewable and sustainable energy research has attracted much attention, probably at least in part because of diminishing supplies and rising prices for fuel in recent years. Researchers have been searching for a practical alternative to petroleum and coal for generation of electrical power. Hydroelectric power stations and wind turbines are two of the most successful solutions in this field. Compared to hydroelectric energy, wind power is much more environmentally friendly of these two alternative energy solutions. Nevertheless, there are some limitations of traditional wind power generators. For example, using a large rotational turbine to harvest energy from the air requires significant financial and infrastructure investment, large real-estate area and long term commitment.
Much previous work has focused on using piezoelectric materials to convert mechanical vibration energy into electrical power. Some research has reviewed recent devices and applications of piezoelectric materials based energy harvesters.
Some research has developed a vibration based piezoelectric generator with a beam configuration, and provided a model for estimating the output voltage and power with experimental validation.
Some research has developed cantilevered power harvesting prototypes with three types of piezoelectric materials: lead zirconium titanate ceramic (PZT), macro fiber composite (MFC), and Polyvinylidene Fluoride (PVDF). The power generating capabilities of these three materials, under large vibration amplitudes, have been compared.
In order to harvest fluid induced energy, some research has designed an “energy harvesting eel” using PVDF, which could convert the flow energy to electrical power in oceans and rivers through a flow induced oscillating motion on the PVDF film, which may be laid over a bluff body.
Some research has designed and optimized a small windmill prototype to extract energy from airflow. In this research a wind driven mechanism was used to bend a series of piezoelectric bimorphs transducers, with the wind driving the rotation of the small windmill.
A variety of other piezoelectric and magnet materials based wind energy generation concepts are known. One proposed device (which has not necessarily been made or enabled) uses passive wind harvesting technology, Polyvinylidene Fluoride (PVDF) and/or piezoelectric ceramic fiber composite material woven into a textile-like material forming artificial leaves and leaf nodes. In this proposed device, each textile “leaf” moves under the force of the wind to transducer electrical power from the wind. The device does not include a cantilever stalk member that undergoes vibrational motion in the manner of a cantilevered member. This proposed device does not include a flat, generally planar piezoelectric stem. This proposed device also does include a pendular member designed to promote cantilevered member type vibrational motion in a cantilever stalk member. The proposed device does not include a plastic or polymer pendular member.
The following published documents may also include helpful background information: (1a) Anton, S. R., and Sodano, H. A., 2007, “A Review of Power Harvesting Using Piezoelectric Materials (2003-2006),” Smart Materials and Structures, 16, pp. R1-R21; (2a) Paradiso, J. A., Starner, T., 2005, “Energy Scavenging for Mobile and Wireless Electronics,” IEEE Pervasive Computing, 4(1), pp. 18-27; (3a) Sodano, H A., Park, G. and Inman, D. J., 2004, “A Review of Power Harvesting from Vibration using Piezoelectric Materials,” The Shock and Vibration Digest, 36(3), pp. 197-205; (4a) Priya, S., 2007, “Advances in Energy Harvesting Using Low Profile Piezoelectric Transducers,” Journal of Electrocerarnics, 19(1), pp. 167-184; (5a) Roundy, S., Wright, P. K., and Rabaey, J., 2003, “A Study of Low Level Vibrations as a Power Source for Wireless Sensor Nodes,” Computer Communications, 26(11), pp. 1131-1144; (6a) Roundy, S., and Wright, P. K., 2004, “A Piezoelectric Vibration Based Generator for Wireless Electronics,” Smart Materials and Structures, 13(11), pp. 1131-1142; (7a) Shen, D., Choe, S., and Kim, D., 2007, “Analysis of Piezoelectric Materials for Energy Harvesting Devices under High-g Vibrations” Japanese Journal of Applied Physics, 46(10A), pp. 6755-6760; (8a) Sodano, H. A, Park, G. and Inman, D. J., 2004, “Estimation of Electric Charge Output for Piezoelectric Energy Harvesting,” Journal of Strain, 40(2), pp. 49-58; (9a) Taylor, G. W., Burns, J. R., Kamman, S. M., Powers, W. B., and Welsh, T. R., 2001, “The Energy Harvesting Eel: A Small Subsurface Ocean/River Power Generator,” IEEE Journal of Oceanic Engineering, 26(4), pp. 539-547; (10a) Allen, J. J., and Smits, A. J., 2001, “Energy Harvesting Eel” Journal of Fluids and Structures, 15, pp. 629-640; (11a) Priya, S., 2005, “Modeling of Electric Energy Harvesting Using Piezoelectric ‘Windmill,” Applied Physics Letter, 87, pp. 184101 (hereinafter “Priya Modeling”); (12a) Myers, R., Vickers, M., Kim, H., and Priya, S., 2007, “Small Scale Windmill,” Applied Physics Letter, 90, pp. 054106 (hereinafter “Priya Small Scale Windmill”); (13a) Ward, L. “Wind Belt—the Latest in Wind Power.” Ecofriend. November 2007. Popular Mechanics, 30 Jan. 2008; (14a) Piezoelectric Trees-aesthetically pleasing wind power, 2002, http://www.halfbakery.com/idea/Piezoelectric—20Trees; (15a) Dickson, R. M., 2008, “New Concepts in Renewable Energy,” especially pp. 33-34; (16a) Williamson, C. H. K., 1996, “Vortex Dynamics in the Cylinder Wake,” Annual Review of Fluid Mechanics, 28, pp. 477-539; (17a) Measurement Specialties, Inc, 2008, “Piezo Film Product Guide and Price List,” pp. 4-6; (18a) Shukla, S., Govardhan, R. N., and Arakeri, J. H., 2009, “Flow Over a Cylinder with a Hinged-Splitter Plate,” Journal of Fluids and Structures, article in press, doi:10.1016/j.jfluidstructs.2008.11.004; (19a) Huang, L., 1995, “Flutter of Cantilever Plates in Axial Flow,” Journal of Fluids and Structures, 9, pp. 127-147; (20a) Argentina, M., and Mahadevan, L., 2005, “Fluid-Flow Induced Flutter of a Flag,” Proceedings of the National Academy of Sciences, 102, pp. 1829-1834; (21a) Tang, L., and Paidoussis, M. P., 2007, “On the Instability and the Post-Critical Behavior of Two-Dimensional Cantilevered Flexible Plates in Axial Flow,” Journal of Sound and Vibration, 305, pp. 97-115; (22a) Eloy, C. Souilliez, C., and Schouveiler, L., 2007, “Flutter of a Rectangular Plate,” Journal of Fluids and Structures, 23, pp. 904-919; (23a) Zhang, J., Childress, S., Libchaber, A., and Shelley, M., 2000, “Flexible Filaments in a Flowing Soap Film as a Model for One-Dimensional Flags in a Two-Dimensional Wind,” Nature, 408, pp. 835-839; (24a) Connell, B. S. H., and Yue, D. K. P., 2007, “Flapping Dynamics of a Flag in a Uniform Stream,” Journal of Fluid Mechanics. 581, pp. 33-67; (25a) Mustafa, G., and Ertas, A., 1996, “Dynamics and Bifurcations of a Coupled Column-Pendulum Oscillator,” Journal of Sound and Vibration, 182(3), pp. 393-413; (26a) Cuvalci, O., and Ertas, A., 1996, “Pendulum as Vibration Absorber Experiments and Theory,” Journal of Vibration and Acoustics, 118, pp. 558-566; (27a) Cuvalci, O., 2000, “The Effect of Detuning Parameters on the Absorption Region for a Coupled System: a Numerical and Experimental Study,” Journal of Sound and Vibration, 229(4), pp. 837-857; (28a) Nayfeh, A. H., and Mook, D. T., 1995, “Energy transfer from high-frequency to low-frequency modes in structures,” Journal of Vibration and Acoustics, 117, pp. 186-195; (29a) Alben, S., and Shelley, M., 2008, “Flapping States of a Flag in an Inviscid Fluid: Bistability and the Transition to Chaos,” Physical Review Letters, 100, pp. 074301; (30a) Wang, Z, and Xu, Y., 2007, “Vibration Energy Harvesting Device based on Air-Spaced Piezoelectric Cantilevers” Applied Physics Letter, 90, pp. 263512; (31a) Kim, F L W., Batra, A., Priya, S., Uchino, K., Markley, D., Newnham, R. E., and Hofmann, H. F, 2004, “Energy Harvesting Using a Piezoelectric ‘Cymbal’ Transducer in Dynamic Environment,” Japanese Journal of Applied Physics, 43, pp. 6178-6183; (32a) Chen, C. T., Islam, R. A., and Priya, S., “Electric Energy Generator,” IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, 53(3), pp. 656-661: (33a) Vestas Wind Systems A/S, Wind Turbine Products' Brochures of V52-850 kW and V90-3.0 MW, http://www.vestas.com/ (hereinafter “VESTAS”); (34a) Bryant M., Garcia E. (2009) “Aeroelastic Vibration Power Harvester Design”, Dynamics, Systems and Control Seminar Series, Ithaca N.Y., Mar. 27, 2009; (4b) S. P. Beeby, M. J. Tudor, and N. M. White, Meas. Sci. Technol. 17, R175 (2006); (9b) A. Erturk, J. Hoffmann, and D. J. Inman, Appl. Phys. Lett. 94, 254102 (2009); (10b) F. C. Moon and P. J. Holmes, J. Sound Vib. 65, 275 (1979); (11b) Supplementary material at http://dx.doi.org/10.1063/1.3525045 for calculation and experiment details; (12b) C. H. K. Williamson and R. Govardhan, Annu. Rev. Fluid Mech. 36, 413 (2004); (13b) S. Shukla, R. N. Govardhan, and J. H. Arakeria, J. Fluids Struct. 25, 713 (2009); (20b) S. Li and H. Lipson, Proceedings of ASME Conference on Smart Materials, Adaptive Structures and Intelligent Systems (ASME, Oxnard, Calif., 2009), pp. 611-619; (11c) G. W. Taylor, J. R. Bums, S. M. Kammann, W. B. Powers, and T. R. Welsh, IEEE J. Ocean. Eng. 26, 539 (2001); (18c) Measurement Specialties. Inc, Piezo Film Product Guide and Price List, (2008); (35c) M. Bryant and E. Garcia, Proc. SPIE, 7288, 728812 (2009); (36c) R. R. Mahadik and J. Sirohi, Proc. ASME Conference on Smart Materials, Adaptive Structures and Intelligent Systems, (ASME, Oxnard, Calif., 2009), pp. 443-450; (38c) MicroBelt tech sheet, http://www.humdingerwind.com/; (39c) Y. K. Tan and S. K. Panda, Proc. Annu. Conf. IEEE Ind. Electron. Soc. (IEEE, Taipei, 2007), pp. 2175-2180; (40c) W. P. Robbins, I. Marusic, D. Morris, and T. O. Novak, Proc. ASME International Mechanical Engineering Congress and Exposition, (ASME, Chicago, Ill., 2006), pp. 581-590; (41c) H. D. Akaydin, N. Elvin, and Y. Andreopoulos, J. Intell. Mater. Struct. 0, 1 (2010); (41c) H. D. Akaydin, N. Elvin, and Y. Andreopoulos, Exp. Fluids. (2010); (43c) S. Pobering, S. Ebermeyer and N. Schwesinger, Proc. SPIE, 7288, 728807 (2009); (44c) N. S. Hudak and G. G. Amatucci, J. Appl. Phys. 103, 101301 (2008).
Description Of the Related Art Section Disclaimer: To the extent that specific publications are discussed above in this Description of the Related Art Section, these discussions should not be taken as an admission that the discussed publications (for example, published patents) are prior art for patent law purposes. For example, some or all of the discussed publications may not be sufficiently early in time, may not reflect subject matter developed early enough in time, may be work of the present inventors and/or may not be sufficiently enabling so as to amount to prior art for patent law purposes. To the extent that specific publications are discussed above in this Description of the Related Art Section, they are all hereby incorporated by reference into this document in their respective entirety(ies).